PDPs are gaining more attention recently as flat display panels since they have more advantageous features than liquid crystal panels, including faster display time, wider viewing angle, ease of manufacturing large screens, and higher display quality realized by self-light emission. PDPs are being used in an expanding range of contexts, including displays for public places and wide-screen display devices for domestic viewing.
In a PDP, gas discharge generates ultraviolet rays, and these ultraviolet rays excite phosphors, which then emit visible light for color display. PDP driving systems can be generally classified into AC and DC types. An electric discharge system can be classified into two types: surface discharge and opposed discharge. An AC surface discharge type that has a 3-electrode structure is a mainstream type with respect to higher definition, larger screens, and easier manufacture. A PDP of the AC surface discharge type that has a 3-electrode structure is configured with multiple pairs of display electrodes aligned in parallel on one substrate, address electrodes disposed on another substrate in a way so as to cross the display electrodes, barrier ribs, and phosphor layers. Since the phosphor layers can be made relatively thick, this type of PDP is appropriate for color displays using phosphors. A method of manufacturing PDPs includes steps of forming panel components such as an electrode, dielectric and phosphor one after another mainly using a step of forming a thick film on a surface of a front substrate and a rear substrate by repeating printing, drying and firing; and overlaying and sealing the front substrate and rear substrate on which these panel components are formed. In the above steps, a firing device is used for drying and firing.
As for the firing device, a so-called roller-hearth kiln, fit for mass production, is employed. The roller-hearth kiln has its transport structure configured by aligning multiple rollers in a direction of transportation of a substrate. While firing the panel components formed on the front and rear substrates, the substrates are placed on a support substrate called a setter (this state is hereafter called a firing target) during transportation for firing to prevent damage to each substrate by the transport structure. In addition, uniform heating of the substrate in its entirety is important when firing the panel components.
However, firing defects occur on the panel components in this type of firing device that seem to be caused by non-uniform heating of the substrate during firing. This appears to be caused by thermal deformation that accumulates in the setter due to repeated use of the setter. Non-uniform contact of the setter and rollers, which are the transportation structure, impedes smooth transportation by meander or deviation, resulting in non-uniform heating while firing a substrate.
The present invention is designed to solve this disadvantage, and aims to offer a method of manufacturing PDPs and a firing device employed in this manufacture that achieve satisfactory firing of panel components by controlling each setter.